Polyester and olefin yarns with basic resins therein wound on core,steamed and acidified with so2 or no2



United States Patent ice the Public H Int. Cl. D06m 3/20 US. Cl. 8-115.54 Claims ABSTRACT OF THE DISCLOSURE The process of uniformly exposingthe surface of a polyhydrocarbon or polyester yarn to an acid treatmentcomprising subjecting said yarn, which has been moistened with water, asby steaming and wound upon a core, to a vacuum and subsequentlysubjecting said yarn to an atmosphere of an acid anhydride vapor, suchas S0 or N0 This invention relates to an improved process for theuniform acid treatment of yarns.

The co-pending patent applications Ser. No. 375,328 filed June 15, 1964,now Patent No. 3,361,843 and Ser. No. 352,317 filed Mar. 16, 1964, nowPatent No. 3,432,- 250 of Robert Miller, Milton Father and Frederick C.Loveless disclose processes for rendering synthetic yarns composedpredominantly of inherently undyeable hydrocarbon or polyester highpolymers deeply dyeable with acid type dyes by first incorporating insaid hydrocarbon or polyester high polymer a quantity of a highly polarbasic polymer and, subsequent to the extrusion of the fibers from thepolymeric composition, uniformly treating the surface of the fibers withan acidic reagant which reacts with some of the highly polar basicpolymer at and near the fiber surfaces. The treatment with the acidicreagent converts a fiber which is only faintly dyeable with acid typedyes to one which can readily be dyed to very deep shades by such typesof dyes. So sensitive is such fiber to this acid activation treatmentthat wherever it is not treated with the acidic reagent to a point ofsubstantial equilibrium, variations in depth of color occur when thefiber is dyed. Thus it is essential to the success of the processesdisclosed in the said copending applications that the activationtreatment with the acidic reagant be performed with a high degree ofuniformity.

Activation treatment procedures involving the continuous passage of thefiber in yarn form through a liquid bath of the acidic reagant isfrequently highly uneconomical because of the amount of activatingreagant carried off on the fiber and because of the cost of rewinding.Batchwise procedures for contacting packages of the yarn wound on coreswith the acidic reagent have inevitably required special precautionswith attendant additional cost to avoid non-uniformity in the activationof the yarn package. 'One such expedient is to wind the yarn onspecially constructed perforated cores in order to assure uniformity ofactivation when such yarn packages are immersed in a liquid bath ofacidic reagant. The rewind-- ing operation to and from such speciallyprepared cores adds considerably to the cost of the yarn. Otherexpedients involve tedious and expensive procedures for circulating theacidic reagant through the packages of yarn.

It is an object of this invention to achieve uniform treatment of yarnwound onto packages by reagents in the vapor state. It is a furtherobject of this invention uniformly to treat yarn wound upon cores withreagants in 3,485,574 Patented Dec. 23, 1969 the vapor state whichcombine with water to form acids. It is a still further object of thisinvention to achieve such treatment without the need for winding theyarn upon specially constructed cores or for unwinding the yarn from thepackage in which it is subjected to the treatment.

These objects, and others which will become apparent from aconsideration of this specification, can be achieved by winding the yarnto be treated in uniformly moistened condition, upon a core, evacuatingthe volume surrounding the said core and subsequently subjecting theyarn thus wound upon the core to an atmosphere of an acid anhydridewhich, upon combining with the moisture on the fiber, forms the acidwhich activates the fiber. The atmosphere of acid anhydride ismaintained in contact with the yarn until equilibrium with the moistureis achieved, i.e. until no further reduction in pressure due to reactionof the acidic reagnat with moisture occurs.

The moisture content of the yarn subjected to treatment by the acidanhydride in the process of this invention must be at leastapproximately 1% O.W.F. (on weight of fiber) in order to result inuniform activation of a marked degree. Ideally, however, the moisturecontent will be 5% O.W.F. or even higher.

The correct moisture content of the fiber or yarn may be achieved bydepositing water upon the yarn either before it is wound upon the coreor thereafter. Inasmuch as the yarn is generally coated with a fiberfinish dis persed or dissolved in water after the spinning and drawingsteps are completed, it is frequently convenient to apply this finishsolution or dispersion in such a fashion that the correct quantity ofwater remains upon the yarn as it is wound upon the core into a package.Care must then be exercised to prevent this moisure from evaporatingduring the interval between the finishing operation and the activationtreatment of this invention. One convenient way to avoid such drying outis to store the packages in polyethylene bags.

If the yarn has not been wound upon cores with a sufiicient amount ofmoisture, or if some has evaporated, this moisture can be imparted tothe yarn by treating the yarn package with steam before the vacuum isapplied. The steam may be saturated or superheated, but its temperatureshould not exceed the temperature above which yarns of the character tobe treated tend to undergo excessive shrinkage, which is C. in the caseof polypropylene.

The moistened yarn wound upon cores is then subjected to a vacuum of atleast 20, but preferably over 27 inches of mercury. Then the spacesurrounding the package of yarn is filled with vapors of the acidanhydride, which upon combination with the water upon the yarn forms theacidic reagent which activates the yarn. If the acid anhydride is amaterial which boils below the treatment temperature, it may beintroduced into the chamber where the treatment is being performed as aliquid and, by raising the temperature above the boiling point, bepermitted to boil so that the vapor fills the space. More conveniently,the acid anhydride is admitted as a gas. As the acid anhydride reactswith the water upon the yarn, the pressure in the chamber in which theactivation is being performed drops. Additional acid anhydride isintroduced either incrementally or continuously to reestablish thedesired pressure by means of a pressure sensitive valve or by manualcontrol. The achievement of equilibrium is signified by cessation of thetendency of the pressure in the chamber to fall, i.e. by the maintenanceof constant pressure in 'the chamber without the further addition ofacid anhydride.

When equilibrium is reached it may be convenient to reapply vacuum tothe chamber in order to remove the unreacted acid anhydride beforeopening the chamber.

The length of time required to achieve equilibrium depends upon theamount of yarn wound upon the packages, the winding pattern and thetightness of the winding, the identity and reactivity of the acidanhydride, the yarn size and extent to which it is bulked, and upon thetemperature.

The process of this invention is particularly suitable for activatingmulti-filament yarns which have been texturized.

The higher the temperature of the activation process, the more rapidlyequilibrium can be reached. However, the upper practical limit oftemperature for thi process is that temperature above which the yarnswhich are to be activated by this process undergo excessive shrinkage,140 C. in the case of polypropylene.

Acid anhydrides suitable for use in this invention are sulfur dioxide,sulfur trioxide, nitrogen dioxide, nitrogen pentoxide, and any othermaterial which, upon combination with water, forms a Bronsted acid.(Bronsted acids are compounds capable of donating a proton in areaction.) The preferred acid anhydrides for use in the process of thisinvention are sulfur dioxide and nitrogen dioxide.

No particular design for the chamber in which the process of thisinvention is to be performed is required. The chamber should be capableof withstanding a vacuum and should not be corroded by the materialsemployed in the process, notably the acid formed by the acid anhydride.It may be convenient to use an autoclave with a removable head tofacilitate the loading and unloading of the packages of yarn to betreated. It is also convenient for the chamber to be fitted with apressure gauge, to permit observation of the progress of the treatmentand the achievement of equilibrium.

The yarns which may conveniently be activated by the process of thisinvention are those disclosed in the said co-pending applications.

The term hydrocarbon polymer is used herein to refer to the matrixmaterial of which the fiber is largely composed. The preferred materialin our invention is polypropylene, and further discussion will be mainlyin terms of this representative hydrocarbon polymer for the sake ofsimplicity of expression. However, the invention is equally applicableto all fiber-forming hydrocarbon linear high polymers, includingpoly-(l-alkenes) such as polyethylene, poly-l-butene,poly(4-methyl-1-pentene), copolymers of two or more l-alkenes,copolymers of nonterminal olefins with l-alkenes, etc.

Examples of the highly polar basic polymers which we incorporate in thehydrocarbon polymers are basic nitrogen-containing materials of thefollowing types.

(1 Thermoplastic polymers of vinyl-substituted monoand polycyclicpyridine bases, either homopolymers or copolymers, including graftcopolymers.

(2) Thermoplastic polyamides, including condensation homopolymers andcopolymers, in which the amide groups are an integral part of thepolymer chain, and addition homopolymers and copolymers having pendantgroups containing or consisting of amide groups.

(3) Amine polymers, including condensation homopolymers and copolymers,in which the amine group is an integral part of the polymer chain, andaddition homopolymers and copolymers having pendant groups which includeor consist of amine groups.

Other basic nitrogen polymers Which may be used are polyurethanes,polyureas, poly(vinylcarbazoles), anilineformaldehyde resins, etc.

The basic nitrogen polymers employed are not extractable from admixturesthereof with the hydrocarbon polymer, under the conditions of treatingand dyeing used. Thus, after a one-hour extraction of the fiber withboiling water at a pH of 3, at least of the originally added nitrogenpolymer should remain in the hydrocarbon polymer. The amount of thebasic nitrogen polymer a ded o the hyd oca bo p ymer h ld be uf c e sothat, after the treatment of the invention, it will bind the amount ofdye required to produce the shade desired. IThe vinyl-substitutedmonocyclic and polycyclic pyridine base dye-receptor polymerincorporated in the hydrocarbon polymer in accordance with the inventionis present either as a homopolymer, or as a copolymer with another vinylmonomer copolymerizable therewith, or as a graft copolymer with ahydrocarbon high polymer. The vinyl-substituted monoand polycyclicpyridine base dyereceptor polymers used as those based, for example, onmonovinylpyridines and monovinylquinolines.

The monovinylpyridines useful in making the above named dye-receptivepolymers include 2-vinylpyridine, 3- vinylpyridine, 4-vinylpyridine,5-methyl-2-vinylpyridine, 2-ethyl 5 vinylpyridine,Z-methyl-S-vinylpyridine, 2- ethyl-6-vinylpyridine,2-isopropenylpyridine, etc. Polymerizable olefinic monomers with whichthe monovinylpyridine may be copolymerized include acrylic andmethacrylic esters typified by ethyl acrylate and methyl methacrylate,vinyl aryl hydrocarbons typified by styrene and vinyltoluenes, andbutadiene-l, 3. Alternatively, the monovinylpyridine may begraft-copolymerized by well known methods with a previously formedlinear high polymer, typified by polyethylene, polypropylene,polystyrene, and polybutadiene. It is always desirable that the basicpolymer contain no more than a minor proportion of materialcopolymerized with a monovinylpyridine, since only the pyridine portionof the polymer additive is active in enhancing the dyeability of thehydrocarbon polymer.

The polyamides useful as the dye-receptors include homopolyamides suchas poly(hexamethylene adipamide), poly(hexamethylene sebacamide),polyvinylpyrrolidinone polycaprolactam, polyenantholactam, andcopolyamides such as Zytel 61 (Du Pont), an interpolymer ofhexamethylene adipamide and hexamethylene sebacamide with caprolactam.

As examples of vinyl polymers with pendant groups consisting of orcontaining amide groups there are the substitutedpoly(vinylpyrrolidinones), e.g., N-vinyl-3- alkylpyrrolidinone, andN-substituted polyacrylamides, e.g., N-butylacrylamide. Also usable arecopolymers of the amide-containing vinyl monomers with other olefinicmonomers such as acrylic and methacrylic esters typified by ethylacrylate and methyl methacrylate, vinyl aryl hydrocarbons typified bystyrene and vinyltoluenes, and butadine-1,3. Alternatively, thevinylpyrrolidinones or acrylamides may be graft-copolymerized bywell-known methods with a previously formed linear high polymer,typified by polyethylene, polypropylene, polystyrene, and polybutadiene.It is always desirable that the basic polymer contain no more than aminor proportion of material copolymerized with the vinylpyrrolidinonesor acrylamides, since only the amide portion of the polymer additive isactive in enhancing the dyeability of the hydrocarbon polymer.

As examples of amine polymers useful as the dye receptor, there are thecondensation products of epihalohydrins or dihaloparaffins with one ormore amines, such as those disclosed in Belgian Patent No. 606,306,exemplified by the condensation product of dodecylamine, piperazine andepichlorohydrin; as examples of addition polymers with pendant groupsconsisting of or containing amines there are the reaction product of astyrene-maleic anhydride copolymer with 3-(dimethylamino)propylamine(the reaction product being a polyamino-polyimide), andstyrene-allylamine copolymers such as those disclosed in US. Patent2,456,428.

The following examples will serve to further illustrate this invention.

EXAMPLE 1 A 375 filament, 3700 denier yarn melt-spun from a polymericcomposition comprising 97% isotatic polypropylene and 3% of a copolymerof equal parts of 2-. vinylpyridine and 2-m y -5-vi y pyridine was t xurizerl and wound by a standard constant tension winding apparatus uponan ordinary cardboard cylindrical core to form a two pound package. Asthe yarn was being wound, it Was placed in contact with a roll wettedwith an aqueous solution of a yarn finish. The yarn package, whichcontained 5% O.W.F. moisture, was placed in an autoclave. The autoclavewas evacuated to 27 inches of mercury, and then sulfur dioxide wasadmitted until the pressure was again raised to one atmosphere. When thesource of sulfur dioxide was shut off, the pressure in the autoclavegradually decreased. Additional increment of sulfur dioxide wereintroduced into the autoclave to keep raising the pressure back toatmospheric. After approximately 10 minutes at room temperature, nofurther incremental additions of S0 were required to maintain thepressure at atmospheric. The autoclave was again evacuated to removeunreacted sulfur dioxide and then opened to remove the yarn package. Theyarn thus treated was subsequently found to be suitable for dyeing inuniform fashion by exposure to acid type dyes.

EXAMPLE 2 A 208 denier, 8 filament yarn melt-spun from a polymericcomposition comprising 97% isotactic polypropylene and 3% Zytel 61,wound upon a cylindrical cardboard core to form a two pound package, wasplaced in an autoclave. The autoclave was evacuated to 27 inches ofmercury. Steam was introduced to raise the total pressure in theautoclave to 23 inches of mercury. N0 was admitted to the autoclave toraise the pressure to atmospheric. Further increments of N0 were addedto maintain the pressure at atmospheric. After approximately 10 minutes,no further additions of N0 were required to maintain the puressure atatmospheric. The autoclave was evacuated, and then opened to remove theyarn. The yarn, after washing, was uniformly dyed to a deep shade oforange with Capracyl Orange R (0.1. No. Acid Orange 178). Another sampleof the same yarn was uniformly dyed blue with Dimacide Light Blue JLAcid Blue 25 (Cl. No. 62055).

Having thus described our invention, that we claim and desire to protectby Letters Patent is:

1. The process of uniformly exposing a yarn compris ing from 90 to 99.5%of a high polymer selected from the class consisting of polyolefins orpolyesters and correspondingly from 10 to 0.5% of a highly polar basicnitrogenous polymer to an acid treatment to render said yarn dyeablewith acid type dyes comprising: winding said yarn upon a core, placingsaid yarn-bearing core into a chamber, evacuating said chamber,introducing sufficient steam into said chamber to uniformly moisten saidyarn with at least 1% (on the Weight of fiber) water, then raising thepressure in said chamber to substantially atmospheric pressure by thesubsequent introduction thereinto of a gas selected from the classconsisting of sulfur dioxide and nitrogen dioxide, and maintaining saidpressure in said chamber at substantially atmospheric pressure byfurther introduction of said gas until equilibrium between said gas andsaid water is substantially established.

2. The process as defined in claim 1 in which the high polymer is apolyolefin.

3. The process as defined in claim 1 in which the high polymer is apolyester.

4. The process as defined in claim 1 in which the high polymer ispolypropylene and the highly polar basic nitrogenous polymer is ahomopolymer vinylpyridine. or copolymer of vinylpyridine with anothervinylpyridine or vinyl monomer copolymerizable therewith.

References Cited UNITED STATES PATENTS 3,361,843 1/1968 Miller et al260857 GEORGE F. LESMES, Primary Examiner D. LEVY, Assistant ExaminerUS. Cl. X.R. 8--31, 55, 100, 149.2, 155.2

